Generally, a passivation layer is a final protection layer of a semiconductor device. The passivation layer is typically formed on an uppermost metal interconnect of the device, and serves to prevent scratching and/or contamination of a foreign substance on a chip surface during the packaging process. Such a passivation layer functions as a means for protecting the semiconductor device from environmental factors such as external moisture. The passivation layer can be formed by a combination of various oxide layers for stress-relief with a nitride layer serving as an excellent protection layer.
In the prior art, the passivation layer has, in some instances, been fabricated by depositing a Plasma Enhanced-Tetra-Ethyl-Ortho-Silicate (PE-TEOS) oxide layer using a Plasma Enhanced Chemical Vapor Deposition (PECVD) on a semiconductor substrate on which an uppermost metal interconnect for the semiconductor device has been formed, and subsequently depositing a SiH4 nitride layer using PECVD. Also, the passivation layer has been fabricated by depositing a SiH4 oxide layer using a high density plasma Chemical Vapor Deposition (HDPCVD) process and subsequently depositing a SiH4 nitride layer using PECVD.
For a semiconductor device such as a multi-interconnect adapted device or a power device, the uppermost metal interconnect, (for example, a metal interconnect made of aluminum) is formed to have a thickness of 8000 to 10000 Å. In contrast, the uppermost metal interconnect of a conventional semiconductor device is formed to have a thickness of 5000 to 6000 Å. Further, the uppermost metal interconnect of the power device is typically formed in a relatively larger area.
However, because the passivation layer experiences a large stress for the thick and wide uppermost metal interconnect, a crack has often occurred in the passivation layer of prior art multi-interconnect adapted devices or prior art power devices during the packaging process. In other words, this stress has caused an increased incidence of defects in semiconductor products that are manufactured using a packaging process.
To reduce the incidence of defects in the semiconductor devices such as cracks of the passivation layer, it has been required that the passivation layer for the uppermost metal interconnect be subjected to low levels of stress, and that the passivation layer be composed of a high hardness material which is resistant to external shocks.